public class fraction {
    public static void main(String[] args) {
        System.out.println("1/1 - 1/2 + 1/3 - 1/4 + 1/5 ...... + 1/99 - 1/100 =");
        double sum = 0;
        int flg = 1;
        for (int i = 1; i <= 100; i++) {
        sum+=1.0/i*flg;
        flg=-flg;
        }
        System.out.println(sum);
    }
}
